Catalysts are used for a wide variety of purposes, for example for alteration of chemical compositions and for decomposition removal of contaminants. Common issues faced when using catalysts include how to maximize the catalyst area that can be used for reaction between the catalyst and the fluid to be treated, while easily and stably carrying, or immobilizing, the catalyst. Catalysts in the form of powders or other particulate forms are able to have maximum catalyst area, but catalytic power cannot be adequately exhibited unless the catalyst particles are oriented in such a manner that the fluid to be treated can flow freely over the entire catalyst area.
The use of expanded PTFE materials as base materials for containing and immobilizing catalyst particles is known (Patent document 1). An expanded PTFE material has a fine porous matrix structure comprising nodes and fibrils, and it allows stable immobilization of catalyst particles by entrapment of the catalyst particles in the interiors of the fine pores. According to Patent document 1, the expanded PTFE porous matrix provides an improved inner surface, or porosity, which allows the contact area between the fluid to be treated and the catalyst particles to be maximized for filtration purposes. An expanded PTFE porous matrix is also advantageous in that it is formed by mechanical stretching without using any chemical reagents such as foaming agents or pore generators, and it is therefore possible to avoid chemical contamination of the catalyst particles that are subsequently immobilized. In addition, since an expanded PTFE porous matrix usually has high mechanical properties including tensile strength, it has excellent manageability and can serve as a catalyst-housing base material with low risk of damage during use.